Refractory block for continuous casting

ABSTRACT

A refractory block for continuous casting is disclosed comprising a unitary assembly including a plate brick having a top, bottom, sides and a passageway therethrough; a gas permeable porous brick having a top, bottom, sides and a passageway therethrough, where the top of the porous brick is attached to the bottom of the plate brick, a gas pool for containing gas surrounds the sides of the porous brick, and a submerged nozzle having a top, bottom and sides, where the sides have shoulder portions, has the top of the submerged nozzle attached to the bottom of the porous brick. A metal casing surrounds the unitary assembly so that the metal casing surrounds and supports a portion of the sides of the plate brick, a portion of the bottom of the plate brick, the sides of porous brick, and a portion of the sides of the submerged nozzle, including the shoulder portions. The metal casing further includes gas feed and discharge pipes therethrough in communication with the gas pool.

INDUSTRIAL FIELD OF THE INVENTION

This invention relates to refractory blocks for slide gate valve whichis used for controlling the flow of a molten steel in continuous castingequipment of the molten steel.

BACKGROUND

From the recent viewpoint of laborsaving it is required to simplify andaccelerate the working of incorporating a brick into a slide gate valve,and therefore it is adopted o integrally set a slide plate and a chutenozzle. Conventionally, in such an integrating method it has beengeneral to set the slide plate and the chute nozzle by using a fillersuch as mortar or castable in a one-body metal casing which is formed toenvelop the side surface and bottom surface of said slide plate and theside surface of said chute nozzle.

However, such a system has demerits in that parallelism can hardly beretained between the sliding surface and the bottom surface of the metalcasing because of the fluidity of the filler, and a long period of timeis required for the complete hardening of the filler.

To remove such demerits the applicant of the present applicationpreviously proposed to employ "an Accommodation Structure of Refractoryfor Slide Valve" (Utility Model Publication No. 2-35405).

By adopting such an accommodation structure it has become to easily takea parallelism of the slide plate, to accelerate adhesion, and to easilymanufacture the refractory block for slide gate valve by ordinarycutting, welding or the like of the steel material. However, with suchan accommodation structure the steel plate fixed to the bottom surfaceof the slide gate valve has no sufficient strength, and it is known thatbecause of thermal expansion of the metal casing a clearance is likelyto occur between the slide plate or seal plate and the mortar-bondedseal nozzle or the submerged nozzle, troubles occasionally occur due tometal insertion or the like, and a complete integration is impossible.

Conventionally, a plate brick and a submerged nozzle are of split type.However, the object of the present invention is to provide a refractoryblock usable for multi-continuous casting in such a way that said platebrick and said submerged nozzle are formed integrally, the integral bodyis covered by a metal casing so that it has in combination a sufficientmechanical strength, a corrosion resistancy, an anti-spalling propertyand the like whereby a clearance is not created in the joint portion,and a nozzle blocking caused by the metal insertion or air suction isprevented so as to improve the quality of steel.

DISCLOSURE OF THE INVENTION

To eliminate the above-mentioned various drawbacks of the known systemthe inventors of the present invention have made intensive, variousstudies and tests, and as a result they have been successful indeveloping the refractory block for continuous casting of the presentinvention. The technical constitution of the invention is such that theouter peripheral surface of that the plate brick accommodated in a metalcasing is joined through mortar or packing with the dowel portion of thesubmerged nozzle accommodated in another cylindrical metal casing, andthe two metal casings are integrally welded together, that the platebrick and the submerged nozzle are formed as a one-body refractoryblock, this block is enclosed by the one-body metal casing whereby saidone-body refractory block may be mounted with the one-body metal casingthrough a castable refractory, that said one-body refractory block maybe combined with a hetero-material refractory, or that a porous brick isinvolved between the plate brick and the submerged nozzle so as to bemounted in a one-body metal casing whereby said porous brick may beprovided with a feed and discharge pipe piercing through the metalcasing.

Further, the present invention is characterized in that a steel sleeveis of such shape that can fit and mount an assembly of the plate brickand submerged nozzle of a continuous casting slide gate valve apparatus,said steel sleeve has a shoulder in the upper portion of the submergednozzle side, and the submerged nozzle and the plate brick are fitted andmounted together through a pressing force-giving ring having a desiredthermal expansion coefficient in the inner peripheral surface of saidshoulder. Furthermore, the invention is characterized in that the steelsleeve mounted with a continuous casting plate brick and the pressingforce-giving ring are internally provided in the shoulder, and the steelsleeve mounted with the submerged nozzle is fitted and welded with them.Alternatively, the shoulder of said steel sleeve may be crossed with orinclined to the axis of the submerged nozzle, or an air-cooling jacketmay be provided in the outer periphery of the steel sleeve.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a vertical sectional view showing a basic embodiment of theinvention;

FIG. 2 is a vertical sectional view of another embodiment wherein ametal casing is welded;

FIG. 3 is a vertical sectional view of still another embodiment whichconsists of a one-body refractory block and a one-body metal casing;

FIG. 4 is a vertical sectional view of still another embodiment whereinthe refractory block is made of a hetero-material;

FIG. 5 is a vertical sectional view of still another embodiment whichcomprises a porous refractory;

FIG. 6 is a vertical sectional view of an embodiment of the invention,which is provided with a pressing force-giving ring;

FIG. 7 is a vertical sectional view similar to FIG. 6, where asplit-type steel sleeve is employed; and

FIG. 8 and FIG. 9 are vertical sectional views of other embodimentswherein an air-cooling jacket is provided in the outer periphery of thesteel sleeve.

THE BEST MODE OF CARRYING OUT THE INVENTION

Some embodiments of the refractory blocks of the present invention willnow be described with reference to the accompanying drawings.

The embodiment shown in FIG. 1 is a refractory block for continuouscasting of the invention, wherein the outer peripheries of a plate brick3 and a submerged nozzle 1 are enclosed directly by a one-body metalcasing 6. The plate brick 3 is constituted to have a recess 4 in thejoint surface with the submerged nozzle 1, a collar portion 2 of thesubmerged nozzle 1 is closely fixed to and fitted in said recess 4thereby forming an assembly, this assembly is enveloped by and fittedinto said one-body metal casing 6, and said collar portion 2 issupported by a shoulder 5 of the metal casing 6.

In this embodiment, the submerged nozzle 1 is made of an ordinarily usedAl₂ O₃ --C or a molten quartz refractory, and the collar portion 2 ofthe submerged nozzle cooperates with the shoulder 5 of the metal casing6 to prevent creation of a clearance in the joint surface with the platebrick. Said recess 4 is of a depth of 1/3 to 1/2 of the thickness of theplate brick, for example a depth of 15 to 20 mm, while the inner surfaceof said recess is made as smooth as possible to closely adhere therecess 4 and the plate brick 3. The metal casing 6 is formed integrallyby an ordinary process with a heat-resistant steel such as ordinarysteel or stainless steel, and in the case of using mortar or a packing 7the metal casing is constituted by high alumina mortar, alumina-carbonmortar or ceramic packing.

The embodiment shown in FIG. 2 is such that a plate brick 25accommodated in a metal casing 24 is connected via mortar or packing 26to a dowel portion 23 of a submerged nozzle 22 previously accommodatedin cylindrical metal casing 21, and said metal casings 21, 24 are joinedtogether by means of spot welding or whole-peripheral welding 27.

In the embodiment illustrated in FIG. 3, the plate brick and thesubmerged nozzle are formed as a one-body refractory block 31, thisblock is fitted in a one-body metal casing 32 through a castablerefractory 33, and it may be possible that without using said castablerefractory the one-body refractory block 31 is enclosed directly by theone-body metal casing 32.

The embodiment shown in FIG. 4 is such that a one-body refractory block41 is constituted by different materials such as Al₂ O₃ --C refractory(C content being 5 to 10% by weight) in portion A and Al₂ O₃ --Crefractory (C content being 25 to 35% by weight) in portion B, and aone-body refractory block 41 constituted by these two kinds of materialsis fitted in and enclosed by a one-body metal casing 42.

FIG. 5 illustrates an embodiment wherein the one-body refractory blockis provided with a porous brick for feeding and discharging gas, and aone-body refractory block is mounted in a one-body metal casing 54, saidone-body refractory block being fitted (preferably an optional dowelportion is provided) with a porous brick 53 between a plate brick 51 anda submerged nozzle 52, said porous brick 53 being ring-shaped (having amolten metal passage opening at its center). A gas pool 55 is providedin the outer periphery of said porous brick 53, and a gas feed anddischarge pipe 56 communicates with said gas pool 55 piercing through ametal casing 54.

FIG. 6 shows a vertical sectional view of the refractory block of theinvention, which is described in claim 1. The reference numeral 101designates a plate brick, and 102 a submerged nozzle. The referencenumeral 110 designates a steel sleeve, this sleeve is of such shape thatit encloses the respective outer peripheries of both the side and bottomsurfaces of said plate brick 101 in its upper stage, and that the middlestage and the lower stage enclose the outer periphery of said submergednozzle 102. That is, the steel sleeve 110 is ordinarily cylindrical, buta shoulder 103 is arranged between the middle stage and the lower stage,and the lower stage is smaller than the middle stage in diameter. Thoughsaid shoulder 103 as illustrated in FIG. 6 forms an inclined shoulderthe shoulder may be one crossing straight with the axis of the submergednozzle 102.

The reference numeral 104 indicates a pressing force-giving ring whichis arranged in the inner circumference of the middle stage of said steelsleeve 110 and which has a desired thermal expansion coefficient, and incase the steel sleeve 110 is made of steel for general structure thepressing force-giving ring 104 is made as a copper ring.

According to the present refractory block as constituted above, thepressing force-giving ring 104 is disposed at a predetermined positionof a steel sleeve 110, the submerged nozzle 102 is fitted in and mountedto the sleeve 110, and then the plate brick 101 is fitted and mountedthereon via the mortar 105. Otherwise an assembly in which the submergednozzle 102 and the plate brick 101 are integrally formed in advance isfitted in and mounted to the steel sleeve 110.

Therefore, if the submerged nozzle riss in temperature to about 700° C.when used for continuous casting the expansion coefficient of the steelsleeve becomes 0.83% and that of the pressing force-giving ring (made ofsteel) 0.15% so that the expansion coefficient of the pressingforce-giving ring is greater by 0.32%. At that time a force of pressingup the submerged nozzle acts thereby resulting in that the joint openingbetween the submerged nozzle and the plate brick can be prevented.

FIG. 7 is a vertical sectional view showing still another embodiment ofthe present invention described in claim 9. The reference numerals sameas those of FIG. 6 show the same members.

In this embodiment, the steel sleeve 110 is split into upper and lowertwo parts, the plate brick 101 is fitted in and mounted to said sleeve110, the pressing force-giving ring 104 is arranged in the upper innerperipheral surface of said shoulder 103 in the steel sleeve 110a havingthe shoulder 103, and thereafter the submerged nozzle 102 is fitted inand mounted to the steel sleeve 110a. Thus the plate brick 101 and thesubmerged nozzle 102 is made an assembly via the mortar 105 while saidsleeves 110, 110a are made one-body by welding at 106 the entireperipheries thereof. Additionally, as shown, said steel sleeves 110 and110a are fitted together by inclining the sleeve 110a inwardly, andtherefore, the outer diameter of the sleeve 110a is approximately equalto the inner diameter of the sleeve 110.

FIG. 8 is a vertical sectional view showing an embodiment wherein theouter periphery of the steel sleeve 110 is provided with an air-coolingjacket 112 having an air discharge opening 112a. Unlike in FIG. 9 saidair-cooling jacket 112 may not be integral with the steel sleeve 110,but it may be constructed by providing a separate member. By cooling theequipment through such constitution it is capable of controlling thethermal expansion of the steel sleeves whereby the force for pressingthe submerged nozzle upward can act to a great extent.

By the above technical constitution the present invention provides thefollowing advantages.

(1) By making the plate brick and the submerged nozzle integral by ametal casing it is possible to prevent a nozzle blocking caused by airsucked from the joint portion to allow the quality of steel to beimproved thereby intending a continuous casting.

(2) It is possible to prevent the nozzle from blocking by sucking andremoving the air occasionally contained in the molten steel, and ifnecessary, by supplying an inert gas.

(3) The plate brick and the submerged nozzle are formed integrally by asteel sleeve, the submerged nozzle is pressed up by making advantage ofthe thermal expansion of the pressing force-giving ring to prevent thejoint opening between said brick and said nozzle whereby troubles causedby air suction can be avoided so as to improve the working efficiency ofthe continuous casting.

We claim:
 1. A refractory block for continuous casting comprising:aunitary assembly comprising:a plate brick having a top, a bottom, sidesand a passageway therethrough; a gas permeable porous brick having atop, a bottom, sides and a passageway therethrough, said top of saidporous brick being attached to said bottom of said plate brick; a gaspool surrounding said sides of said porous brick for containing a gas;and a submerged nozzle having a top, a bottom and sides, said sides ofsaid submerged nozzle having a shoulder portion, said top of saidsubmerged nozzle being attached to said bottom of said porous brick; anda metal casing surrounding said unitary assembly such that said metalcasing surrounds/and supports a portion of said sides of said platebrick, a portion of said bottom of said plate brick, said sides of saidporous brick and a portion of said sides of said submerged nozzleincluding said shoulder portion, said metal casing having a gas feed anddischarge pipe therethrough in communication with said gas pool.
 2. Arefractory block for continuous casting comprising:a unitary assemblycomprisinga plate brick having a top, a bottom, sides and a passagewaytherethrough, and a submerged nozzle having a top, a bottom, sides and apassageway therethrough, said sides of said submerged nozzle having ashoulder portion, said bottom of said plate brick being joined to saidtop of said submerged nozzle; a metal casing surrounding and supportingsaid unitary assembly such that said metal casing surrounds and supportsa portion of said sides of said plate brick, a portion of said bottom ofsaid plate brick and a portion of said sides of said submerged nozzleincluding said shoulder portion; and a pressing ring made from amaterial with a different coefficient of expansion than that of saidmetal casing, said press ring mounted within said metal casing andpositioned to exert a force on said submerged nozzle to urge saidsubmerged nozzle toward said plate brick when the temperature of saidpressing ring increases.
 3. A refractory block as in claim 2, whereinsaid metal casing comprises two parts, an upper part surrounding aportion of said sides of said plate brick and a portion of said bottomof said plate brick and a lower part surrounding a portion of said sidesof said submerged nozzle including said shoulder portion, said upperpart of said metal casing being attached to said lower part of saidmetal casing such that said distance between said portion of said upperpart supporting said bottom of said plate brick and said portion of saidlower part supporting said shoulder portion of said submerged nozzle maybe varied before attachment.
 4. A refractory block as in claim 2,further comprising an air cooling jacket surrounding said metal casing.5. A refractory block as in claim 3, further comprising an air coolingjacket surrounding said metal casing.